Updating data objects on a system

ABSTRACT

A computer system includes a first server including a first data management module and a second server including a second data management module, and a first and second storage controller. The first and second storage controllers are interconnected by a network configured for reliable data multicasting. The computer system further includes a cross system manager for controlling one or more core storage functions on each of the first and second storage controllers. The computer system further includes computer program instructions to, responsive to a core storage function triggered by the cross system manager: Create a multicast group for each of the first server and the second server in the network, wherein the multicast group is created by a reliable multicast mechanism, and Multicast data write operations of each of the first server and the second server to the first storage controller and the second storage controller of the multicast group.

BACKGROUND

The present invention relates generally to updating data objects and inparticular to updating data objects across a storage area network.

Generally, storage network environments allow for the movement of dataobjects, whether from a host server to a storage server or from astorage controller to another storage controller. The movement of dataobjects may be necessary for a variety of reasons, including criticaldata protection and accessing data (e.g., asynchronous and/orsynchronous replication of data, mirroring of data, live guestrelocation from one server to another, etc.). For example, in the caseof replicating or mirroring data, a relationship may exist between acluster (i.e., group) of host servers or a cluster of storagecontrollers, wherein a primary data object is replicated into one ormore replica data objects between the cluster of host servers and/orstorage controllers. The replication process may be performed eithersynchronously or asynchronously.

SUMMARY

A computer system includes one or more computer processors, one or morecomputer readable storage media, a first server including a first datamanagement module and a second server including a second data managementmodule, and a first storage controller and a second storage controller.The first storage controller and the second storage controller areinterconnected by a network. The network is configured for reliable datamulticasting. The computer system further includes a cross systemmanager. The cross system manager controls one or more core storagefunctions on each of the first storage controller and the second storagecontroller. The computer system further includes computer programinstructions stored on the one or more computer readable storage media.The computer program instructions include instructions to, responsive toa core storage function triggered by the cross system manager: Create amulticast group for each of the first server and the second server inthe network, wherein the multicast group is created by a reliablemulticast mechanism, and Multicast data write operations of each of thefirst server and the second server to the first storage controller andthe second storage controller of the multicast group.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system 200 suitable for updating dataobjects using a multicast group in accordance with at least oneembodiment of the invention.

FIG. 2 is a detailed block diagram of a system 200 suitable for updatingdata objects using reliable multicasting in accordance with at least oneembodiment of the invention.

FIG. 3 is a detailed block diagram of a system 200 suitable formirroring data objects using a multicast group in accordance with atleast one embodiment of the invention.

FIG. 4 is a flowchart diagram depicting a flow of events for a corestorage function for mirroring data objects using a multicast group inaccordance with at least one embodiment of the invention.

FIG. 5 is a flowchart diagram depicting operational steps for updatingdata objects using a multicast group in accordance with at least oneembodiment of the invention.

FIG. 6 is a block diagram depicting components of a computer 600suitable for executing at least one embodiment in accordance with thepresent invention.

DETAILED DESCRIPTION

Referring now to various embodiments of the invention in more detail,FIGS. 1 through 3 provide a computer system 200 for updating dataobjects. Computer system 200 includes servers 10, 30 storage controllers42, 44 interconnected over network 50. In an embodiment of theinvention, network 50 may be a multicast network. In an embodiment ofthe invention, a reliable multicast protocol may be added as a layer ontop of the multicast network. Server 10 includes data management module14 and server 30 includes data management module 34, wherein datamanagement modules 14 and 34 manage data cache 16 and data cache 36,respectively. Computer system 200 further includes a cross systemmanager 80, wherein cross system manager 80 may control core storagefunctions of storage controllers 42, 44 (shown in FIG. 2).

Embodiments of the present invention may be used, in response to a corestorage function triggered by cross system manager 80, for:

-   -   creating a multicast group 60 for servers 10, 30 over network 50        by a reliable multicast mechanism; and    -   (ii) multicasting data write operations from servers 10, 30 to        storage controllers 42, 44, respectively, within multicast group        60.

FIG. 1 is a block diagram of a system 200 suitable for updating dataobjects using multicast group 60 in accordance with at least oneembodiment of the invention. FIG. 1 provides only an illustration of oneimplementation and does not imply any limitations with regard to theenvironments in which different embodiments may be implemented. Manymodifications to the depicted environment may be made by those skilledin the art without departing from the scope of the invention as recitedby the claims.

System 200 includes servers 10, 30. Server 10 includes data cache 16 anddata management module (“DMM”) 14. Server 30 includes data cache 36 andDMM 34. In an embodiment, Servers 10, 30 may be a physical server. In analternative embodiment, servers 10, 30 may be a virtual server. In anembodiment, data cache 16 and data cache 36 may be a solid state device.

Servers 10, 30 are interconnected to storage controllers 42, 44,respectively, of storage cluster 40, over network 50. In an embodimentof the invention, network 50 may be a storage area network (“SAN”) thatutilizes a fibre channel protocol (“FCP”). In an alternative embodimentof the invention, network 50 may be an SAN that utilizes an Internetprotocol (“IP”).

Storage controller 42 and storage controller 44 include a host portmanager (“HPM”) 46 and a HPM 48, respectively, as well as a storagedevice 52 (marked LUN 10) and a storage device 54 (marked LUN 10*),respectively. The * symbol denotes that data objects are updated fromstorage device 52 to storage device 54 via system 200.

Multicast group 60 includes servers 10, 3, storage controllers 52, 54.In an embodiment, multicast group 60 may be identified by a world-wideunique identifier (“WWNN) corresponding to network adapters 24 and 26,respectively. In an embodiment, multicast group 60 may be identified bya unique identifier (“UI”) corresponding to storage devices 52 and 54,respectively.

According to a computer-implemented method of the present invention,multicast group 60 is created based on a target and LUN nexus(WWNN-LUN), wherein “WWNN” denotes the name of the storage controllernode for its respective LUN. Servers 10 and 30 may use the LUN nexus tojoin multicast group 60. In the case of critical storage operations(e.g., real time migration, replication, and mirroring), a new storagecontroller 42, 44 may join multicast group 60. Since new storagecontrollers 42, 44 receive live updates from servers 10 and 30, it isnot necessary to resend the modified data objects during the previouslymentioned critical storage operations. Furthermore, since a reliablemulticast protocol may be added as a layer on top of the multicastnetwork, all of the data sent is guaranteed to reach all of the memberof multicast group 60.

HPM 46 and HPM 48 may give priority to the data received on multicastgroup 60 over updates received via a bulk copy mechanism. Once themigration of data objects is complete, the original storage controllers42 and 44 may leave multicast group 60. Here, servers 10 and 30 maycontinue to write to the new storage controllers 42 and 44 of multicastgroup 60. In the case of real time mirroring, all storage controllers 42and 44 may remain in multicast group 60 and receive live updates.Furthermore, if servers 10 and 30 have an input/output (“I/O”) cacheenabled, since servers 10 and 30 are updated, the data objects also getupdated with every write on multicast group 60. Thus, all updates ofdata objects from first server 10 to second sever 30 may be accomplishedvia multicast group 60 in a single step (S10). At step S10, system 200writes data to multicast group 60, which subsequently multicasts thedata to server 30, storage controller 42, and storage controller 44. TheHPMs 46 and 48 give priority to data received via multicast group 60over updates received via a bulk copy mechanism. In other words, system200 is configured for processing data received by first storagecontroller 42 and/or second storage controller 44 via a multicast havinga higher priority over other data received via network 50. HPMS 46 and48 are configured for processing data traffic from multicast group 60over data received during core storage functions since the data trafficfrom multicast group 60 has a higher priority.

FIG. 2 is a detailed block diagram of a system 200 suitable for updatingdata objects using reliable multicasting in accordance with at least oneembodiment of the invention. In FIG. 2, the cross system manager 80 maybe implemented as a distributed system in system 200, wherein crosssystem manager 80 is connected to server 10, server 30, storagecontroller 42, and storage controller 44 via connection 82. Host portmanagers 46 and 48 are implemented on first storage controller 42 andsecond storage controller 44, respectively, to manage their respectivecorresponding network adaptors 24 and 26. Storage network adapters 18,38 and storage controllers 42, 44 include host bus adaptors 20, 22 thatprovide access to first server 10, second server 30, and storage devices52, 54.

The embodiment, shown in FIG. 2, includes of a cluster of physicalservers 10, 30 (server 1 and server 2) connected to a storage areanetwork (SAN) 50 with the storage controllers 42, 44 (SC1, SC2) via anetwork of connectors, the host bus adapters (HBA) 20 (IP1 . . . IP4)and 22 (TP1 . . . TP8), as well as switches 58 (e.g., fibre channelswitches). Data from the servers 10, 30 may be sent via the HBAs 20 viaswitches 58 (step S20) to the HBAs 22 (step S22). Here, storagecontrollers 42, 44 of SAN 50 are responsible to hold (i.e., “store”) andtransmit data objects to servers 10, 30. In an embodiment of theinvention, each storage controller 42, 44 is physically partitioned intounits. In an embodiment of the invention, each storage controller 42, 44is logically partitioned into units. The units of each storagecontroller 42, 44 may be presented to servers 10, 30 as logical units(LUNs) 52, 53, 54, 55. Each LUN 52, 53, 54, 55 in storage controllers42, 44 may be uniquely identified by a 64 bit identifier (i.e., “LUNidentifier” or “LUN number”), where an asterisk symbol (*) placed afterthe LUN number (e.g., LUN10*, LUN21*, etc.) indicates the destinationLUN for the core storage operations. The logical units may be based onany storage controller architecture types, including, but not limited tosymmetric or asymmetric active-active, and asymmetricactive—standby/passive.

Each storage controller 42, 44 may have a storage cache managed by acache manager 62, 64 used to improve performance by holding frequentlyaccessed storage objects. In an embodiment of the invention, each server10, 30 may house an operating system 12. In an alternative embodiment,each server 10, 30 may house a hypervisor 32, respectively. Servers 10,30 are connected to SAN 50 via network adapter (HBA) 20. In anembodiment of the invention, servers 10, 30 may include solid statedrives, which are used as local data cache storages 16, 36 to improveI/O performance.

In an embodiment of the invention, the transport technology of SAN 50may be based on a fibre channel network (FCP SAN). In an alternativeembodiment, the transport technology of SAN 50 may be based on othertransportation technologies, including, but not limited to an IP basedSAN.

Data management modules (DMM) 14, 34 may manage I/O caches 16, 36 ofservers 10, 30 and works with the reliable multicast mechanism (RMM) 66to ship I/O to SAN 50. Host port modules (HPM) 46, 48 may manage thehost facing ports of the storage controller working with the reliablemulticast manager to ensure that peers get delta updates as priorityfrom servers 10, 30 during the core storage functions involving storagecontroller 42 to storage controller 44 bulk data movements.

The multicast group (MCG) 60 for each storage LUN 52, 53, 54, 55,including an HBA 22 and one or more servers 10, 30 subscribing each LUN52, 53, 54, 55 may be created. This multicast group 60 is uniquelyidentified in a storage domain using the World Wide Node Name (WWNN) andthe LUN ID.

When a write operation at servers 10, 30 is requested to the LUN 52, 53,54, 55, the I/O may be multicast to all members of multicast group 60,including storage controllers 42, 44 using the reliable multicastmechanism. Thus, data coherency may be maintained across multicast group60, and consequently, storage cluster 40 as well.

FIG. 3 is a detailed block diagram of a system 200 suitable formirroring data objects using a multicast group in accordance with atleast one embodiment of the invention. In FIG. 3, system 200 is anenlarged system that includes a third storage controller 45 andcorresponding devices storage network adapter 27, HPM 49, cache manager65 and LUN 56. Furthermore, the HBAs 20 are named from IP1 to IPN, andthe HBAs 22 from TP1 to TPN, where N is a natural number.

According to a computer-implemented method for mirroring data objectsfrom server 10 to second server 30, cross system manager 80 may createmulticast group 60 with the world-wide unique identifier (WWNN) of thecorresponding storage network adapter 24 of the corresponding storagecontroller 42 of first server 10. In an alternative embodiment, crosssystem manager 80 may create multicast group 60 with the uniqueidentifier (LUN) of the corresponding storage device 52 of thecorresponding storage controller 42. According to thecomputer-implemented method, cross system manager 80 may furtherinitiate a core storage function for mirroring, from first storagecontroller 42 to second storage controller 44. According to thecomputer-implemented method, data management module 34 of second server30 may join multicast group 60, followed by host port manager 48 ofsecond storage module 44. According to the computer-implemented method,once data management module 34 and host port manager 48 have joinedmulticast group 60, host port manager may initiate the mirroringfunction. According to the computer-implemented method, upon initiatingthe mirroring function, first server 10 may continue I/O operations tostorage device 52. Furthermore, according to the computer-implementedmethod, data management module 14 of first server 10 multicasts the datato storage controllers 42, 44 being a member of the multicast group 60using reliable multicasting. Accordingly, to the computer-implementedmethod, host port manager may give priority to the data received onmulticast group 60. According to the computer-implemented method, in thecase of mirroring data from server 10 to server 30, first storagecontroller 42 stays in multicast group 60. On the other hand, in thecase of migrating data from first server 10 to second server 30, firststorage controller 42 leave multicast group 60. As depicted in FIG. 3,the data has been mirrored to storage devices 54, 56 (denoted by LUN10*, and LUN 10**, respectively).

FIG. 4 is a flowchart diagram depicting a flow of events for a corestorage function for mirroring data objects using a multicast group inaccordance with at least one embodiment of the invention. At step (S1),multicast group 60 is created based on target and LUN nexus (WWNN-LUN),with the first member (WWNN) indicating the storage controller node namefor its respected LUN. Once multicast group 60 is created, then hostservers 10, 30 may join multicast group 60. At step (S2), cross systemmanager 80 may initiate the core storage function (e.g., mirroring,replication, etc.) at the source storage controller (SC1) 42,(represented by HPM 46) to migrate the data of LUN 52 to a destinationstorage controller (SC2) 44 (represented by HPM 48. As depicted in FIG.4, the units are LUN10 52 to LUN10* 54 from SC1 42 to SC2 44.

At step (S3), servers 10 and 30, which are interested in the data, mayjoin multicast group 60 via data management modules 14 and 34,respectively. At step (S4), whenever a core storage function needs to beperformed, destination storage controller (SC2) 42 may join multicastgroup 60. At step (S5), servers 10, 30 may continue to perform I/Ooperations via multicast group 60 as part of its normal operation.

At step (S6), source storage SC1 42 may perform the core storagefunction (replication/mirroring) from LUN10 52 to LUN10* 54. At step(S7), all writes or updates from servers 10, 30 are reliably multicastto storage controllers 42, 44 in multicast group 60, thereby ensuringdata object coherency. At step (S8), during the core storage functionoperation, HPM 48 of the destination source controller (SC2) 44 may givepriority to the data received on multicast group 60 over data receiveddirectly from the source storage controller (SC1) 42. At step (S9), thecore storage function from SC1 42 to SC2 44 is completed and ends. Inthe case of mirroring, source storage controller (SC1) 42 may remain inmulticast group 60. On the other hand, in the case of migration, sourcestorage controller (SC1) 42 may leave multicast group 60.

FIG. 5 is a flowchart diagram depicting operational steps for updatingdata objects using a multicast group in accordance with at least oneembodiment of the invention. At step (S102) cross system manager 80 maymanage the configuration for the core storage functions for updatingdata objects from a source to a target storage controller LUN. At step(S104), multicast group 60 may be created based on the target and LUNnexus. Here, the first member of multicast group 60 is source storagecontroller 52. At step (S106), servers 10 and 30, which are interestedthe data, may join multicast group via data management modules 14 and34, respectively. At step (S108), whenever a core storage function needsto be performed, storage controllers 42, 44 may join multicast group 60.At step (S110), servers 10 and 30 may continue with regular read/writeoperations. Here, HPM 46 updates the source LUN 52.

At step (S112), the direction of the input/output (i.e., read or write)operation of servers 10 and 30 may be determined. Responsive todetermining a read option at step (S112), at step (S114), data is cachedand processed by cache managers 62, 64 at the servers 10, 30,respectively.

On the other hand, responsive to determining a write option at step(S112), at step (S116), data management modules 14, 34 may send the datavia reliable multicast via cache managers 62, 64. Furthermore, at step(S116), HPMs 46, 48 of storage controllers 42, 44, respectively, mayupdate the contents of LUNs 52, 54. Furthermore, at step (S116), guestoperating systems 12, 32 may receive a completion signal. At step(S118), HPMs 46, 48 of source storage controllers 42, 44 may execute thecore storage function.

At step (S120), the write data of servers 10, 30 is automaticallyupdated via multicasting to the source and target LUNs 52, 54 via HPMs46, 48. Here, HPMs 46, 48 prefer delta updates via updates received bymulticast group 60 over updates received by a core storage function.

At step (S122), it may be determined whether the core storage functionis complete. If it is determined that the core storage function is notcomplete, the flow loops back to step (S118). If it is determined thatthe core storage function is complete for a migration case, then at step(S124), storage controllers 42, 44, including source LUN 52, 54, mayleave multicast group 60. If it is determined that the core storagefunction is complete for a mirroring case, then at step (S124), storagecontrollers 42, 44, including source LUN 52, 54 may remain in multicastgroup 60.

Some embodiments of the present invention may include one, or more, ofthe following features, characteristics, operations and/or advantages:(i) a system that uses a reliable multicast group including allparticipating servers and storage controllers instead of separatesynchronization steps between servers and storage controllers; (ii) adata management module that exploits performance and accuracies in areliable multicast mechanism, where the system takes advantage of thehigh performance, unique message-to-packet mapping of the reliablemulticast mechanism, which ensures a delay-free, high-speed datadelivery mechanism that delivers millions of messages per second withsub-million latencies; (iii) a reliable multicast mechanism that worksindependently regardless of whether the transport of data is multicastor unicast; (iv) a system having a data management module, host portmodule and reliable multicast module that are installable components,which may be implemented in software, firmware or microcode that cancoexist independently as kernel components in each server or storagecontroller; (v) a cross system manager that may be part of anyvirtualization management application which has the visibility tomanage, monitor and control the virtualization aspects of the system ofthe present invention; (vi) a system that allows for the efficientmigration, mirroring, and replication of data objects across multiplestorage controllers; (vii) a system that eliminates chatter betweenstorage controllers for live delta updates (e.g., incremental updatesduring the mirroring process need not be tracked and copied from a firststorage controller to a second storage controller as the second storagecontroller is already part of the multicast group; (viii) a system thatresults in significant time improvements for mirroring and/orreplication, especially for rapidly changing data; and (ix) a systemwhere concurrent data objects may be updated in a steady state withoptimal transactions across multiple servers and storage controllers.

FIG. 6 is a block diagram depicting components of a computer 600suitable for executing at least one embodiment in accordance with thepresent invention. FIG. 6 displays the computer 600, the one or moreprocessor(s) 604 (including one or more computer processors), thecommunications fabric 602, the memory 406, the RAM 616, the cache 618,the persistent storage 608, the communications unit 612, the I/Ointerfaces 614, the display 622, and the external devices 620. It shouldbe appreciated that FIG. 6 provides only an illustration of oneembodiment and does not imply any limitations with regard to theenvironments in which different embodiments may be implemented. Manymodifications to the depicted environment may be made.

As depicted, the computer 600 operates over a communications fabric 602,which provides communications between the computer processor(s) 604,memory 606, persistent storage 608, communications unit 612, andinput/output (I/O) interface(s) 614. The communications fabric 602 maybe implemented with any architecture suitable for passing data orcontrol information between the processors 604 (e.g., microprocessors,communications processors, and network processors), the memory 606, theexternal devices 620, and any other hardware components within a system.For example, the communications fabric 602 may be implemented with oneor more buses.

The memory 606 and persistent storage 608 are computer readable storagemedia. In the depicted embodiment, the memory 606 comprises a randomaccess memory (RAM) 616 and a cache 618. In general, the memory 606 maycomprise any suitable volatile or non-volatile one or more computerreadable storage media.

Program instructions and data used to practice embodiments of thepresent invention may be stored in the persistent storage in thepersistent storage 608, or more generally, any computer readable storagemedia, for execution by one or more of the respective computerprocessors 604 via one or more memories of the memory 606. Thepersistent storage 608 may be a magnetic hard disk drive, a solid statedisk drive, a semiconductor storage device, read-only memory (ROM),electronically erasable programmable read-only memory (EEPROM), flashmemory, or any other computer readable storage media that is capable ofstoring program instructions or digital information.

The media used by the persistent storage 608 may also be removable. Forexample, a removable hard drive may be used for persistent storage 608.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer readable storage medium that is also part of the persistentstorage 608.

The communications unit 612, in these examples, provides forcommunications with other data processing systems or devices. In theseexamples, the communications unit 612 may comprise one or more networkinterface cards. The communications unit 612 may provide communicationsthrough the use of either or both physical and wireless communicationslinks. In the context of some embodiments of the present invention, thesource of the various input data may be physically remote to thecomputer 600 such that the input data may be received and the outputsimilarly transmitted via the communications unit 612.

The I/O interface(s) 614 allow for input and output of data with otherdevices that may operate in conjunction with the computer 600. Forexample, the I/O interface 614 may provide a connection to the externaldevices 620, which may be as a keyboard, keypad, a touch screen, orother suitable input devices. External devices 620 may also includeportable computer readable storage media, for example thumb drives,portable optical or magnetic disks, and memory cards. Software and dataused to practice embodiments of the present invention may be stored onsuch portable computer readable storage media and may be loaded onto thepersistent storage 608 via the I/O interface(s) 614. The I/Ointerface(s) 614 may similarly connect to a display 622. The display 622provides a mechanism to display data to a user and may be, for example,a computer monitor.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a readable storage medium that can direct acomputer, a programmable data processing apparatus, and/or other devicesto function in a particular manner, such that the computer readablestorage medium having instructions stored therein comprises an articleof manufacture including instructions which implement aspects of thefunction/act specified in the flowchart and/or block diagram block orblocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof computer program instructions, which comprises one or more executableinstructions for implementing the specified logical function(s). In somealternative implementations, the functions noted in the block may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A computer-implemented method, comprising:identifying, by one or more processors, a request directed to a firstserver to perform a core storage function for a first data object storedon a first storage device, wherein the core storage function is at leastone of: (i) real-time replication, (ii) real-time mirroring, or (iii)real-time migration; generating, by one or more processors, in responseto identifying the request to perform the core storage function, amulticast group that includes at least: (i) the first server, (ii) afirst storage controller located on the first storage device, (iii) asecond server and (iv) a second storage controller located on a secondstorage device; and multicasting, by one or more processors, one or moredata write operations associated with the core storage function to: (i)the first storage controller, (ii) the second server and (iii) thesecond storage controller included in the multicast group.
 2. Thecomputer-implemented method of claim 1, further comprising: updating, byone or more processors, based on the one or more data write operationsmulticasted to the multicast group being for real-time replication orreal-time mirroring: (i) the first data object stored on the firststorage device and (ii) a second data object stored on the secondstorage device, wherein the second data object is a replica of the firstdata object.
 3. The computer-implemented method of claim 2, furthercomprising: maintaining, by one or more processors, the first storagecontroller and the second storage controller in the multicast group inresponse to updating the first data object and the second data object.4. The computer-implemented method of claim 1, further comprising:migrating, by one or more processors, based on the one or more datawrite operations multicasted to the multicast group being for real-timemigration, the first data object from the first storage device to thesecond storage device.
 5. The computer-implemented method of claim 4,further comprising: removing, by one or more processors, the firststorage controller and the second storage controller from the multicastgroup in response to migrating the first data object from the firststorage device to the second storage device.
 6. The computer-implementedmethod of claim 1, further comprising: processing, by one or moreprocessors, the one or more data write operations associated with thecore storage function received via multicast in priority to data writeoperations received via a bulk copy mechanism.
 7. Thecomputer-implemented method of claim 1, wherein the multicast group isidentified by at least one of a world-wide unique identifier and aunique identifier.
 8. A computer program product, the computer programproduct comprising one or more computer readable storage media andprogram instructions stored on the one or more computer readable storagemedia, the program instructions comprising instructions to: identify arequest directed to a first server to perform a core storage functionfor a first data object stored on a first storage device, wherein thecore storage function is at least one of: (i) real-time replication,(ii) real-time mirroring, or (iii) real-time migration; generate, inresponse to identifying the request to perform the core storagefunction, a multicast group that includes at least: (i) the firstserver, (ii) a first storage controller located on the first storagedevice, (iii) a second server and (iv) a second storage controllerlocated on a second storage device; and multicast one or more data writeoperations associated with the core storage function to: (i) the firststorage controller, (ii) the second server and (iii) the second storagecontroller included in the multicast group.
 9. The computer programproduct of claim 8, further comprising program instructions to: update,based on the one or more data write operations multicasted to themulticast group being for real-time replication or real-time mirroring:(i) the first data object stored on the first storage device and (ii) asecond data object stored on the second storage device, wherein thesecond data object is a replica of the first data object.
 10. Thecomputer program product of claim 9, further comprising programinstructions to: maintain the first storage controller and the secondstorage controller in the multicast group in response to updating thefirst data object and the second data object.
 11. The computer programproduct of claim 8, further comprising program instructions to: migrate,based on the one or more data write operations multicasted to themulticast group being for real-time migration, the first data objectfrom the first storage device to the second storage device.
 12. Thecomputer program product of claim 11, further comprising programinstructions to: remove the first storage controller and the secondstorage controller from the multicast group in response to migrating thefirst data object from the first storage device to the second storagedevice.
 13. The computer program product of claim 8, further comprisingprogram instructions to: process the one or more data write operationsassociated with the core storage function received via multicast inpriority to data write operations received via a bulk copy mechanism.14. The computer program product of claim 8, wherein the multicast groupis identified by at least one of a world-wide unique identifier and aunique identifier.
 15. A computer system, the computer systemcomprising: one or more computer processors; one or more computerreadable storage media; computer program instructions; the computerprogram instructions being stored on the one or more computer readablestorage media for execution by the one or more computer processors; andthe computer program instructions comprising instructions to: identify arequest directed to a first server to perform a core storage functionfor a first data object stored on a first storage device, wherein thecore storage function is at least one of: (i) real-time replication,(ii) real-time mirroring, or (iii) real-time migration; generate, inresponse to identifying the request to perform the core storagefunction, a multicast group that includes at least: (i) the firstserver, (ii) a first storage controller located on the first storagedevice, (iii) a second server and (iv) a second storage controllerlocated on a second storage device; and multicast one or more data writeoperations associated with the core storage function to: (i) the firststorage controller, (ii) the second server and (iii) the second storagecontroller included in the multicast group.
 16. The computer system ofclaim 15, further comprising program instructions to: update, based onthe one or more data write operations multicasted to the multicast groupbeing for real-time replication or real-time mirroring: (i) the firstdata object stored on the first storage device and (ii) a second dataobject stored on the second storage device, wherein the second dataobject is a replica of the first data object.
 17. The computer system ofclaim 16, further comprising program instructions to: maintain the firststorage controller and the second storage controller in the multicastgroup in response to updating the first data object and the second dataobject.
 18. The computer system of claim 15, further comprising programinstructions to: migrate, based on the one or more data write operationsmulticasted to the multicast group being for real-time migration, thefirst data object from the first storage device to the second storagedevice.
 19. The computer system of claim 18, further comprising programinstructions to: remove the first storage controller and the secondstorage controller from the multicast group in response to migrating thefirst data object from the first storage device to the second storagedevice.
 20. The computer system of claim 15, further comprising programinstructions to: process the one or more data write operationsassociated with the core storage function received via multicast inpriority to data write operations received via a bulk copy mechanism.